The present invention relates to cross country ski bindings of the type described in commonly assigned co-pending application Ser. No. 818,741, filed July 25, 1977. The subject matter of said application is incorporated herein by reference thereto, to the extent desired to facilitate an understanding of the present invention.
The noted copending application relates to a cross country binding with a forward supporting or bracing element for a shoe sole that engages the supporting element. A forward sole elongation engages the supporting element in such a manner that the sole can be lifted off the ski at its rear end whereby the sole elongation can be springingly locked to the ski automatically. Such a binding, with secure retention of the shoe, ensures a lifting off of the heel of the shoe from the ski which is necessary for cross country skiing, and non-fatiguing application of the ski [to the ground] even when there is a snow layer underneath, as well as stable and simple inexpensive construction, independent of the size of the shoe sole.
The present invention relates to the problem of ensuring a still better adaptation of the binding to the natural running motion of the foot, especially so that the skier will have a particularly unhindered lift of the heel from the ski.
Accordingly, the invention contemplates providing that a rear part of the supporting element which can clampingly accept the sole elongation is connected with a front part of the supporting element that is fixed on the ski, so as to be movable at an angle in the lifting-off direction of the shoe sole.
In particularly preferred embodiments, the arrangement is such that the axis of rotation for the angular movement of the rear part of the bracing element, running crosswise to the long axis of the ski, is disposed ahead of the sole elongation or at least in the forward zone thereof. The axis of rotation is determined by a hinge pin, or as an ideal axis of rotation with corresponding elastic deformation of the supporting element or of parts thereof according to various preferred embodiments of the invention.
The invention has the effect that the sole elongation is not itself rigidly connected with the ski. For this reason, the heel of the shoe can lift off freely from the ski in fast skiing, without being hindered by rigid clamping of the toe part of the shoe in the supporting element, and without causing fatigue over the long run.
In a special preferred embodiment of the invention, the lifting off of the rear part of the supporting element which can be lifted from the ski with angular movement occurs against a spring action that urges this part back toward the ski. The skier will thereby receive the necessary secure feeling of connection with the ski. On the other hand, the part that is lifted off with angular motion will return to the ski as soon as it is relieved of the load of the skier's shoe, and thus be ready for the ski to be set down again [on the ground surface].
Mobility between the part that receives the shoe sole elongation with angular mobility and the part of the supporting element that is fixed to the ski can be made either articulated or elastic by the springing elements in accordance with preferred embodiments of the invention. Preferred embodiments provide that the rear part that is angularly movable is connected with the front part that is fixed to the ski by means of torsion springs. Other preferred embodiments provide that the angularly-movable part bears against the part fixed to the ski, or directly against the ski, by means of an elastic element and a lever arm cooperating with it.
The use of rubber pads is particularly advantageous according to still other contemplated embodiments, said pads being torsion or pressure stressed, for example, and also rubber-metal parts where the rubber is vulcanized onto the metal. Use of metallic parts that slide on each other may thereby be reduced to a minimum.
An especially simple and inexpensive embodiment of the invention consists in use of wire springs that suitably are braced on the part fixed to the ski, and load the angularly-movable part which serves to accept the shoe sole elongation in a direction that presses against the ski.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, several embodiments in accordance with the present invention.